jdesalvo

Me again...

So according to the wiring diagrams
the wires to the boost plug are
B,B/W,Br/W,Br/R

I have a Black/White, Brown/White, Brown/Red, and Brown/Black

Is B supposed to be the Brown/Black???

I assume the boost gauge should go to 0 when the engine is keyed on and not started. Is this correct? Also, can someone give me a rough idea of where the Brown/Red wire branches off to go the boost gauge?

Currently the car fires, then immediately dies...

NZConvertible

Yes, the sensor ground wire on early S4's is brown/black, then changed to black for later S4's.

Correct.

You can see on the wiring diagram that after it branches the boost gauge wire goes through connector FEM-01, which is an 8x2-pin plug by the passengers foot just after the harness passes into the cabin. It probably branches near where the bundle of wires going to FEM-01 braches from the harness.

That's not a MAP sensor problem. It sounds more like the AFM is disconected or has a bad connection.

jdesalvo

Thanks NZ. I'm sure the car has multiple issues. I figured i'd start with obvious hacked up connector and no zero on the boost gauge. I did some checking with the volt meter and found that I had 12v on black and roughly .2 on the reference and output wires. Applying vacuum did not change the output.

NZConvertible

With the ignition turned on there should be 5V from the ECU at the Vref (Br/W) wire. If there isn't check the other 5V sensors (AFM and TPS) to see if their Br/W has 5V (it's all the same cirucit). If they do then it's a wiring problem, maybe at the connector. If they don't it might be an ECU problem. Check the Vref supply at the ECU (pin 2A).

ECU pin-out: https://www.rx7club.com/attachment.p...hmentid=165722

jdesalvo

Yep - Just what I was thinking...

Dropped by the garage during my lunch and checked it out -

Pin 2a at the ecu = 0.3v

Got a new ECU on the way from ebay. Getting an N333 to replace the N332.

If I used a 12v and 5v power supply to power the sensors, would I be able to check them all out? I'd hate to install a new ECU and burn it up.